I've been thinking about different ways to make STR/2hander builds viable, so thinking of making a Double-sided Weapon build, as I've never made one... threw together the below build to take advantage of Double Sided Momentum and some of the Two-Weapon Defense builds. Does this look viable? Any suggestions re changes/optimisations? I've never played a Ranger before either so if anyone has any info on good Favoured Enemies that would be useful also

Can't see anything obviously wrong.
Are you going Dragon Disciple for any particular reason?
I tend to pick Favoured Enemies that are immune to crits, or are rather tough. I'd probably avoid Animals, as those aren't usually an issue, and they are split into Animals, Vermin, Beasts and Magical Beasts. Maybe Elementals instead?

What's your AC going to look like? I'd guess it might be too low and without any Concealment, Crit Immunity, DR or Epic Dodge you're probably going to be a bit squishy. I guess it depends on what you mean by viable.